Broadband dielectric spectroscopy and calorimetric investigations of d-lyxose

Singh, Lokendra P.; Alegría, Ángel; Colmenero, Juan

doi:10.1016/j.carres.2011.06.029

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…Representative fit results for this binary system at a fixed temperature are shown in Figure 2(b). From this figure, it is clear that the nature of the low frequency process (process-I) is similar to those observed in pure glass formers as well as hydrated samples [2][3][4]6,7]. This indicates that it is due to the cooperative motion of homogeneous mixture which is plasticized and becomes faster in the presence of water.…”

Section: Resultssupporting

confidence: 69%

Glass transition phenomena in D-xylose aqueous solutions: A broadband dielectric spectroscopy study

Singh¹

2016

AIP Conference Proceedings

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Broadband dielectric measurements for D-xylose-water mixture with x w = 0.30 & 0.40, were performed in the frequency range of 10 mHz to 10 MHz and in the temperature range of 150 K to 260 K. Differential scanning calorimeter was also carried out to see the thermal behavior of this aqueous solutions. Two relaxation processes were observed, in addition to the contribution of dc conductivity in the low frequency side. The lower frequency process, the so-called primary relaxation process (process-I), is responsible for the glass transition (T g) whereas the faster one or high frequency process (designated as process-II) is due to the reorientational motion of the water molecules.

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Section: Resultssupporting

confidence: 69%

Glass transition phenomena in D-xylose aqueous solutions: A broadband dielectric spectroscopy study

Singh¹

2016

AIP Conference Proceedings

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“…The effect of vitrification associated with the secondary glass transition at T gb is much weaker than that of the structural a-relaxation at T ga . Nevertheless, the effect was observed in different glass-formers by various kinds of calorimetry, 24,30,41,42 and by positronium annihilation lifetime spectroscopy (PALS). [43][44][45][46] These techniques directly determine T gb .…”

Section: Introductionmentioning

confidence: 99%

“…This observation 30 of the JG b-relaxation endotherm and its characteristic hysteresis is the first. Previous workers had not found them in their calorimetric studies of glass-formers, 31,32,41,42,48 and the JG b-relaxation had only been inferred from the calorimetric data.…”

Section: Introductionmentioning

confidence: 99%

Coupling of caged molecule dynamics to Johari-Goldstein β-relaxation in metallic glasses

Wang

Ngai

Wang

et al. 2016

Journal of Applied Physics

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Three recently published papers have discovered a general property of the fast caged dynamics observed in the glassy states of polyalcohols (S. Capaccioli et al., J. Phys. Chem. B 119, 8800 (2015)), amorphous polymers (K. L. Ngai et al., J. Phys. Chem. B 119, 12502 (2015)), and van der Waals molecular glass-formers (K. L. Ngai et al., J. Phys. Chem. B 119, 12519 (2015)). The fast caged dynamics are manifested as nearly constant loss (NCL) in dielectric and mechanical susceptibility. Shown before in these papers is the intensity of the caged dynamics change temperature dependence at a temperature THF nearly coincident with the secondary glass transition temperature Tgβ, at which the Johari-Goldstein (JG) β-relaxation time τJG reaches ∼103s. Evidently this finding indicates the coupling of the caged dynamics to the secondary glass transition. The glass-formers considered so far are all soft matters. However, the generality of the phenomenon and its explanation implies that the relation, THF - Tgβ, should be observed in other classes of glass-formers. In this paper, we extend the consideration of the phenomenon and explanation to metallic glasses, which are not soft matter. The experimental data presented show the same phenomenon, supporting its generality and fundamental importance in the physics of glass and glass transition

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“…The calorimetric and volumetric effects associated with the secondary glass transition at T gβ are much weaker than the structural α-relaxation at T gα but are observable in some glass-formers by various kinds of precision calorimetry − and by positronium annihilation lifetime spectroscopy (PALS). − These techniques directly determine T gβ . A recent experiment has detected the secondary glass transition and determined T gβ of a well aged metallic glass by differential scanning calorimetry, showing that the nonequilibrium glassy state is characterized by two fictive temperatures: the higher one corresponding to the kinetic freezing of cooperative α-relaxation and the lower one corresponding to the kinetic freezing of β-fluctuations.…”

Section: Introductionmentioning

confidence: 99%

“…The calorimetric and volumetric effects associated with the secondary glass transition at T g is much weaker than the structural -relaxation at T g , but was observable in some glassformers by various kinds of precision calorimetry [12][13][14][15][16][17] , and by positronium annihilation lifetime spectroscopy (PALS) [18][19][20][21] . These techniques directly determine T g .…”

Section: Introductionmentioning

confidence: 99%

Coupling of Caged Molecule Dynamics to JG β-Relaxation III:van der Waals Glasses

et al. 2015

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In the first two papers separately on the polyalcohols and amorphous polymers of this series, we demonstrated that the fast dynamics observed in the glassy state at high frequencies above circa 1 GHz is the caged dynamics. We showed generally the intensity of the fast caged dynamics changes temperature dependence at a temperature THF nearly coincident with the secondary glass transition temperature Tgβ lower than the nominal glass transition temperature Tgα. The phenomenon is remarkable, since THF is determined from measurements of fast caged dynamics at short time scales typically in the ns to ps range, while Tgβ characterizes the secondary glass transition at which the Johari-Goldstein (JG) β-relaxation time τJG reaches a long time of ∼10(3) s, determined directly either by positronium annihilation lifetime spectroscopy, calorimetry, or low frequency dielectric and mechanical relaxation spectroscopy. The existence of the secondary glass transition originates from the dependence of τJG on density, previously proven by experiments performed at elevated pressure. The fact that THF ≈ Tgβ reflects the density dependence of the caged dynamics and coupling to the JG β-relaxation. The generality of the phenomenon and its theoretical rationalization implies the same should be observable in other classes of glass-formers. In this paper, III, we consider two archetypal small molecular van der Waals glass-formers, ortho-terphenyl and toluene. The experimental data show the same phenomenon. The present paper extends the generality of the phenomenon and explanation from the polyalcohols, a pharmaceutical, and many polymers to the small molecular van der Waals glass-formers.

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Broadband dielectric spectroscopy and calorimetric investigations of d-lyxose

Cited by 9 publications

References 38 publications

Glass transition phenomena in D-xylose aqueous solutions: A broadband dielectric spectroscopy study

Glass transition phenomena in D-xylose aqueous solutions: A broadband dielectric spectroscopy study

Coupling of caged molecule dynamics to Johari-Goldstein β-relaxation in metallic glasses

Coupling of Caged Molecule Dynamics to JG β-Relaxation III:van der Waals Glasses

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